Refrigeration apparatus

Abstract

A refrigeration apparatus includes a compressor and a controller. The compressor has a casing and a compression element. Compressed refrigerant is sent out of the casing after being discharged into an internal space of the casing. An oil sump formed in the casing collects refrigerator oil. A heater heats the refrigerator oil collected. The controller controls the heater while the refrigeration apparatus is stopped so that a temperature of the refrigerator oil collected in the oil sump reaches a first oil temperature target value. The first oil temperature target value is set in order to keep a refrigerant condensation amount of the refrigerant equal to or less than an allowable condensation amount at which the concentration or viscosity of the refrigerator oil needed to lubricate the compressor can be maintained. The refrigerant condensation amount is caused by in-dome condensation at the start of operation of the refrigeration apparatus.

What is claimed is: 
     
       1. A refrigeration apparatus, comprising:
 a compressor having a casing, a compression element and a structure arranged so that refrigerant compressed by the compression element is sent out of the casing after being discharged into an internal space of the casing, an oil sump being formed in the casing to collect refrigerator oil, and a heater being disposed in the casing to heat the refrigerator oil collected in the oil sump; and 
 a controller configured to control the heater while the refrigeration apparatus is stopped so that a temperature of the refrigerator oil collected in the oil sump reaches a first oil temperature target value, 
 the controller being further configured to set the first oil temperature target value in order to keep a refrigerant condensation amount of the refrigerant equal to or less than an allowable condensation amount at which the concentration or viscosity of the refrigerator oil needed to lubricate the compressor can be maintained, with the refrigerant condensation amount being caused by in-dome condensation in which the refrigerant discharged from the compression element into the internal space at the start of operation of the refrigeration apparatus is condensed in the internal space before being sent out of the casing. 
 
     
     
       2. The refrigeration apparatus according to  claim 1 , wherein
 the controller is further configured
 to determine the allowable condensation amount based on an amount of the refrigerator oil collected in the oil sump while the refrigeration apparatus is stopped, and 
 to set the first oil temperature target value so that the refrigerant condensation amount caused by the in-dome condensation is equal to or less than the allowable condensation amount. 
 
 
     
     
       3. The refrigeration apparatus according to  claim 1 , wherein
 while the refrigeration apparatus is stopped, the controller is further configured
 to determine a second oil temperature target value at which the concentration or viscosity of the refrigerator oil collected in the oil sump in a state of solution equilibrium can be maintained at a concentration or viscosity of the refrigerator oil needed to lubricate the compressor, and 
 to control the heater so that the temperature of the refrigerator oil collected in the oil sump reaches a higher one of the first oil temperature target value and the second oil temperature target value. 
 
 
     
     
       4. The refrigeration apparatus according to  claim 2 , wherein
 while the refrigeration apparatus is stopped, the controller is further configured
 to determine a second oil temperature target value at which the concentration or viscosity of the refrigerator oil collected in the oil sump in a state of solution equilibrium can be maintained at a concentration or viscosity of the refrigerator oil needed to lubricate the compressor, and 
 to control the heater so that the temperature of the refrigerator oil collected in the oil sump reaches a higher one of the first oil temperature target value and the second oil temperature target value.